API Bulk: The Final Frontier

Traditionally Postmark has focused on sending only transactional messages with the highest deliverability standards, and that’s produced a ton of loyal fans that boast we’re the best in the business! *blushing* But if we can accommodate more types of messages with the same high-quality sending standards, many of our customers prefer us as their sole email provider.

Our mission 🛰 is to make email painless and enjoyable for development teams, and we're in the unique position to both preserve our world-class 🌎 transactional service and superior deliverability while using that experience to build the ultimate bulk sending environment in parallel♊︎. So I’m pleased to announce that we’ve launched 🚀 brand new infrastructure for managing what we call “API bulk”, that is, similar messages sent to multiple recipients.

Those who’ve been testing it here for the past 6 months have seen truly stellar ✨ and consistently fast deliverability that I’m over-the-moon 🌜about! Of course, the goal is to be more universal 🔭 about the kinds of messages Postmark can support, but so far selected customers have been sending mainly app updates, release notes, daily digests, and event invitations. I’m personally on the lookout for developers willing to go boldly 👩‍🚀 into more use-cases, so this is where you come in!

Please make contact 👽 if you’re interested in trying out Postmark API Bulk, and my team would love to chat about your specific sending practices and volume requirements. We always want to optimize our tooling and services to best support developers, ensuring your email needs and Postmark are always a match made in heaven 🌤.

Questions you might have #

Are you just trying to make more money? #

To clarify our goals for this project, we definitely aren't trying to compete with the likes of Mailchimp or other email marketing platforms. This project is just an attempt to fill in the gaps we see in transactional vs. bulk messages, to be able to send more of that grey area mail that may not be pure marketing/promotional but does need to go out to multiple recipients at once. Traditionally we rejected all messages like this, which based on feedback from our customers split their app's messages across multiple providers. Our goal is to be able to accept more of those high quality, high engagement messages to make life easier for devs.

So you’re just accepting everyone as a customer now? #

Postmark will never be an open door to any sender. We're still manually vetting each potential customer, chatting with them one-on-one about what they send and why. Unlike some other providers who accept almost anyone who will hand them money or free data, we're dedicated to supporting only senders who follow and exceed best practices. Of course just in case someone is especially clever at hiding their intentions, we've also built internal anti-abuse systems that not only help us analyze all senders' performance but can stop potentially spammy messages before they’re even sent. Our API Bulk project has provided even more opportunities to build on and improve those systems that preserve our exceptional deliverability and high standing with receiving ISPs.

Won’t this affect transactional mail? #

Based on our experience, we have always recommended separating bulk and transactional traffic using different sending IPs and From domains. They have entirely different origins as well as vulnerabilities, and so following our own advice we’ve chosen to create a separate but parallel infrastructure for them. That means transactional and bulk traffic do not mix in Postmark, including when it comes to IP ranges. This follows best practices for separating email reputation as recommended by inbox providers like Gmail.

Do you have any documentation on how to send API Bulk? #

If your account is approved for sending bulk messages, we'll recommend working with the /batch endpoint for sending to a maximum of 500 recipients at once, opening up to 10 concurrent connections.

Anna Ward

Anna Ward

Head of Deliverability and professional picnicker.

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